Patch 5.4.0 (10-Sep-2013) Combustion on targets affected by the Mage's Ignite now deals additional damage equal to 20% of Ignite's damage per tick (down from 50%).

Patch 5.1.0 (27-Nov-2012): Combustion's periodic damage is now based only on the current Ignite, instead of both Ignite and Pyroblast. Damage has been increased to bring it up to approximately the same level as before.

Patch 4.1.0 (26-Apr-2011): Combustion no longer has a global cooldown.